Mehrdad Negahban
University of Nebraska-Lincoln, NE·Engineering
Plastics like polycarbonate are glasses: rigid, disordered solids that never fully settle into equilibrium. Their stiffness and strength drift over time, depending on how they were heated, cooled and deformed.
- Fields
Engineering
Materials Science
Physics
- Topics
polymer glasses
glassy polymers
glass transition
- Grants
- 1 known grant, through Mar 2027
What they work on
- Extend the Back Stress Expansion model of glassy polymers to include a distribution of relaxation times, the range of timescales over which polymer chains rearrange.
- Capture in the model the shift from steep (super-Arrhenius) temperature dependence of relaxation above the glass transition to a weaker dependence in the glassy state.
- Generalize the model to a full multi-dimensional framework so it can describe non-isotropic and large, nonlinear deformations of polymer glasses.
- Validate the model using new pressure-dependent structural recovery, constant-volume (isochoric) and nonlinear viscoelastic measurements on polycarbonate, polysulfone and PMMA.
More about the research
Engineers cannot reliably predict how such polymer glasses behave after years of service. That gap holds back their use in electronic thin films and in structural composites for aircraft, cars and wind turbines.
Why it matters
Polymer glasses appear in aerospace, automotive and wind turbine composites and in electronic thin films, but their properties shift with age and use, so designers struggle to estimate part lifetimes. A validated predictive model could let engineers design these materials and components with more confidence in their long-term mechanical and thermal behavior.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
Closest labs
Yuhang Hu
Georgia Institute of Technology, GA·Engineering
Formulate thermodynamically consistent constitutive laws from statistical models of evolving polymer networks, so that growth, degrowth, remodeling and stiffness change emerge from coupled reaction, transport and deformation.
Neda Maghsoodi
University of Southern California, CA·Materials Science
Measure how focused ultrasound produces localized heating, phase transition, deformation, and recovery in programmed liquid crystal elastomers, recording temperature fields, deformation histories, and material properties across ultrasound conditions and material architectures.
You-Yeon Won
Purdue University, IN·Materials Science
Determine how micelle shape controls interfacial mechanics by comparing spherical and cylindrical poly(styrene)-poly(ethylene glycol) micelles spread at the air-water interface, using Langmuir isotherms, X-ray reflectivity, grazing-incidence X-ray scattering, and Brewster angle microscopy.
The school
University of Nebraska-Lincoln: 17 labs on PI Pages, $657M a year on research, 261 research doctorates a year.
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